A patient with microcytic hypochromic anemia, normal or elevated RBC count, and target cells on peripheral smear is suspected of having a hemoglobinopathy. Which test would be most appropriate to confirm the diagnosis?

1. A

   Serum iron and TIBC

2. B

   Bone marrow biopsy

3. C

   Serum ferritin estimation

4. D

   Hb electrophoresis

Appeared in: INI-CET EXAM -2025

Explanation

• The patient's presentation with microcytic hypochromic anemia, a normal or elevated RBC count, and target cells on a peripheral smear is classic for a thalassemia syndrome, a type of hemoglobinopathy.
• Hb electrophoresis is the definitive diagnostic test because it directly separates and quantifies different types of hemoglobin in the blood.
• This allows for the identification of abnormal hemoglobin variants (like HbS in sickle cell) or abnormal ratios of normal hemoglobins (like an elevated HbA2 in β-thalassemia trait), which confirms the diagnosis of a hemoglobinopathy.

Why Other Options Were Wrong

• Option A: These tests assess iron status. While useful for ruling out iron deficiency anemia (the most common cause of microcytic anemia), they do not identify or confirm a structural or quantitative defect in hemoglobin itself. Iron levels can be normal or high in thalassemia.
• Option B: A bone marrow biopsy is an invasive procedure that is not required for the initial diagnosis of a common hemoglobinopathy like thalassemia. The diagnosis can be confirmed with peripheral blood tests.
• Option C: Serum ferritin measures the body's iron stores. It helps differentiate iron deficiency from other anemias but does not identify the type of hemoglobin. In thalassemia, ferritin levels are often normal or elevated due to ineffective erythropoiesis and potential iron overload.

Related Visual

• Visual 1: Peripheral Blood Smear - An image showing microcytic (small), hypochromic (pale) red blood cells alongside characteristic target cells (codocytes) to help learners visualize the key findings mentioned in the stem.
• Visual 2: Diagram of Hb Electrophoresis Results - A comparative diagram showing a normal Hb electrophoresis pattern versus the pattern seen in β-thalassemia trait, highlighting the elevated HbA2 peak.

Clinical Relevance

• Nursing practice connection: Use the key finding related to Diagnosis of Hemoglobinopathies to guide bedside assessment, documentation, and the next nursing action.
• Accurate diagnosis of a hemoglobinopathy like thalassemia trait is crucial for genetic counseling. Patients need to understand the risk of having a child with a more severe form of the disease (thalassemia major) if their partner is also a carrier.
• It prevents misdiagnosis and inappropriate treatment. Treating a patient with thalassemia with iron supplements (thinking it's iron deficiency) can lead to harmful iron overload.
• What if? If the patient's RBC count was low instead of normal/elevated, the initial suspicion would shift strongly towards iron deficiency anemia. In that case, serum iron, TIBC, and serum ferritin would become the most appropriate initial tests, and Hb electrophoresis would be a secondary consideration if iron studies were normal.

How to Approach the Question

• First, analyze the key laboratory findings presented in the question: microcytic hypochromic anemia, normal/elevated RBC count, and target cells.
• Recognize that while microcytic hypochromic anemia is common in iron deficiency, the normal or elevated RBC count is a specific clue that points away from iron deficiency and towards thalassemia.
• Consider the term 'hemoglobinopathy.' This refers to a disorder of the hemoglobin molecule itself.
• Evaluate the options based on what they measure. Serum iron, TIBC, and ferritin all relate to iron metabolism.
• A bone marrow biopsy is an invasive test for cellular production issues.
• Hb electrophoresis is the only test listed that directly analyzes the hemoglobin protein types. Therefore, to 'confirm' a 'hemoglobinopathy,' this is the most specific and appropriate test.

Concept Tested & Keywords

• Concept Tested: Diagnosis of Hemoglobinopathies
• Stem keywords: microcytic hypochromic anemia, normal or elevated RBC count, target cells, hemoglobinopathy
• Lead-in keywords: most appropriate, confirm the diagnosis
• Clinical cues: The combination of microcytic anemia with a normal/elevated RBC count is a strong indicator for thalassemia, differentiating it from iron deficiency anemia.

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